Oxygen Impurity in Cubic Boron Nitride Thin Films Prepared by Plasma-enhanced Chemical Vapor Deposition

Cubic boron nitride thin films were prepared by inductively-coupled plasma-enhanced chemical vapor deposition(ICP-CVD).The influences of base pressure and oxygen concentration on the content of oxygen impurity for cubic boron nitride film deposition were investigated.It was found that approximately 2% of oxygen impurity can still be detected in cubic boron nitride films even under a base pressure of up to 1×10-5Pa.Moreover,a new infrared(IR) absorption peak near 1230-1280 cm-1 was detected by Lorentzian-type curve fitting when the oxygen impurity content reached more than 3 at%.O1s core-level X-ray photoelectron spectroscopy(XPS) measurements confirmed the existence of B-O bond in boron nitride films.Therefore,this new peak could be attributed to the antisymmetric B-O stretching vibration of the trigonal BO3 group.Moreover,the intensity of this new peak was found to increase with oxygen impurity concentration linearly.Thus the oxygen impurity content in cubic boron nitride films could be evaluated quasi-quantitatively from the intensity of this new IR absorption peak.